Field
This disclosure relates to communication networks. More specifically, the present disclosure relates to a system and method for a constructing a scalable switching system based on hierarchical overlay tunneling.
Related Art
The exponential growth of the Internet has made it a popular delivery medium for a variety of applications running on physical and virtual devices. Such applications have brought with them an increasing demand for bandwidth. As a result, equipment vendors race to build larger and faster switches with versatile capabilities, such as network virtualization and multi-tenancy, to accommodate diverse network demands efficiently. However, the size of a switch cannot grow infinitely. It is limited by physical space, power consumption, and design complexity, to name a few factors. Furthermore, switches with higher capability are usually more complex and expensive. More importantly, because an overly large and complex system often does not provide economy of scale, simply increasing the size and capability of a switch may prove economically unviable due to the increased per-port cost.
One way to increase the throughput of a switch system is to use layer-2 switch stacking. In switch stacking, multiple smaller-scale, identical switches are interconnected in a special pattern to form a larger logical switch. However, switch stacking requires careful configuration of the ports and inter-switch links. The amount of required manual configuration becomes prohibitively complex and tedious when the stack reaches a certain size, which precludes switch stacking from being a practical option in building a large-scale switching system. Furthermore, a system based on stacked switches often has topology limitations which restrict the scalability of the system due to bandwidth considerations.
A flexible way to improve the scalability of a switch system is to build an interconnection of switches that can be controlled in a cohesive way, these switches can often share a single logical chassis, or a single control plane (referred to as “fabric switch”). A fabric switch is a collection of individual member switches. These member switches form a network of interconnected switches that can have an arbitrary number of ports and an arbitrary topology. As demands grow, customers can adopt a “pay as you grow” approach to scale up the capacity of the fabric switch.
While a fabric switch brings desirable features, some issues remain unsolved in efficient formation and data transportation of a scalable fabric switch. One challenge that remains is that as layer-2 networks become more ubiquitous, extended layer-2 broadcast domains are hosting an increasing number of medium-access-control (MAC) addresses. In addition, the emergence of cloud computing based on virtual machines exacerbates the grown of the number of MAC addresses. How to manage such a large number of MAC addresses, while providing the capability of handling a large amount of layer-2 traffic, remains a main challenge for network equipment vendors.